The Bryan/College Station (B/CS) region has been reported to have elevated concentrations of dissolved organic carbon (DOC) in surface water. Increased DOC concentrations are worrisome as DOC has been shown to be an energy source for the recovery and regrowth of E. coli and many watersheds are impaired by high bacteria levels. To examine the sources and fates of DOC in rural and urban regions to better understand DOC movement though the environment, seven watersheds were studied. To investigate source, streams were analyzed using diffuse reflectance near infrared spectroscopy (DR-NIR) and carbon isotopes. Fate of DOC was determined through monthly streams samples, gathered between March 2011 and February 2012, which were incubated for biodegradable DOC (BDOC). Soil in the region was sampled based on land use categories. Soil was analyzed for DOC and BDOC as well as DOC adsorption, the other major fate of DOC. Above ground vegetation was sampled in conjunction with soil and analyzed for BDOC. Data indicated that fecal matter from cliff swallows provided considerable organic material to streams in the B/CS region as shown through DR-NIR. Carbon isotope values in streams ranged from -23.5 +/- 0.7% to -26.8 +/- 0.5%. Stream spectra may be able to predict carbon isotope values in streams (Adj. R2 = 0.88). Mean annual stream DOC concentrations ranged from 11 +/- 3 mg/L to 31 +/- 12 mg/L, which represents a significant decrease in DOC between 2007 and 2011. Concurrent increases in pH and conductivity were also recorded. The decrease in DOC and the increases in pH and conductivity may be due to impacts of high sodium irrigation tap water. Biodegradable DOC was low in streams, which is likely due to DOC being present in streams in refractory forms that are resistant to microbial breakdown. Soil chemistry, including soil adsorption, was greatly influenced by sodium. The elevated adsorption coefficients and release values seen in highly developed and urban open areas can be attributed to frequent exposure to high sodium irrigation water. The results indicate that sodium is a major driver of DOC in the system. Sound management decisions concerning irrigation water chemistry and urban development might eventually emerge to protect water quality as a result of this research.

In 2007 the production of expanded polystyrene (EPS) in the world was over 4 million tonnes and is expected to grow at 6 percent per year. With the increased concern about environmental protection, alternative biodegradable materials from renewable resources are of interest. The present doctoral thesis work successfully demonstrates that starch-based foams with mechanical properties similar to EPS can be obtained by reinforcing the cell-walls in the foams with cellulose nanofibers (MFC). High cellulose nanofiber content nanocomposites with a highly plasticized (50/50) glycerol-amylopectin starch matrix are successfully prepared by solvent-casting due to the high compatibility between starch and MFC. At 70 wt% MFC, the nanocomposites show a remarkable combination of high tensile strength, modulus and strain to failure, and consequently very high work to fracture. The interesting combination of properties are due to good dispersion of nanofibers, the MFC network, nanofiber and matrix properties and favorable nanofiber-matrix interaction. The moisture sorption kinetics (30% RH) in glycerol plasticized and pure amylopectin film reinforced with cellulose nanofibers must be modeled using a moisture concentration-dependent diffusivity in most cases. The presence of cellulose nanofibers has a strong reducing effect on the moisture diffusivity. The decrease in zero-concentration diffusivity with increasing nanofiber content could be due to geometrical impedance, strong starch-MFC molecular interaction and constrained swelling due to the cellulose nanofiber network present. Novel biomimetic starch-based nanocomposite foams with MFC contents up to 40 wt% are successfully prepared by freeze-drying. The hierarchically structured nanocomposite foams show significant increase in mechanical properties in compression compared to neat starch foam. Still, better control of the cell structure could further improve the mechanical properties. The effect of cell wall composition, freeze-drying temperature and freezing temperature on the resulting cell structure are therefore investigated. The freeze-drying temperature is critical in order to avoid cell structure collapse. By changing the starch content, the cell size, anisotropy ratio and ratio between open and closed cells can be altered. A decrease in freezing temperature decreases the cell size and increases the anisotropy ratio. Finally, mechanical properties obtained in compression for a 30 wt% MFC foam prepared by freeze-drying demonstrates comparable properties (Young's modulus and yield strength) to expanded polystyrene at 50% RH and similar relative density. This is due to the reinforcing cellulose nanofiber network within the cell walls. / QC 20100913

The goal of this project was to develop a non-toxic amphiphilic diblock copolymer nanoparticulate drug delivery system that will solubilize paclitaxel (PTX) and retain the drug in plasma. Methoxy poly(ethylene glycol)-block-poly(ε-caprolactone) (MePEG-b-PCL) diblock copolymers loaded with PTX were characterized and their physicochemical properties were correlated with their performance as nanoparticulate drug delivery systems. A series of MePEG-b-PCL was synthesized with PCL blocks ranging from 2-104 repeat units and MePEG blocks of 17, 44 or 114 repeat units. All copolymers were water soluble and formed micelles except MePEG₁₁₄-b-PCL₁₀₄, which was water insoluble and formed nanospheres. Investigation of the effects of block length on the physicochemical properties of the nanoparticles was used to select appropriate copolymers for development as PTX nanoparticles. The critical micelle concentration, pyrene partition coefficient and diameter of nanoparticles were found to be dependent on the PCL block length. Copolymers based on a MePEG molecular weight of 750 g/mol were found to have temperature dependent phase behavior. Relationships between the concentration of micellized drug and the compatibility between the drug and core-forming block, as determined by the Flory-Huggins interaction parameter, and PCL block length were developed. Increases in the compatibility between PCL and the drug, as well as longer PCL block lengths resulted in increased drug solubilization. The physicochemical properties and drug delivery performance characteristics of MePEG₁₁₄-b-PCL₁₉ micelles and MePEG₁₁₄-b-PCL₁₀₄ nanospheres were compared. Nanospheres were larger, had a more viscous core, solubilized more PTX and released it slower, compared to micelles. No difference was seen in the hemocompatibility of the nanoparticles as assessed by plasma coagulation time and erythrocyte hemolysis. Micellar PTX had an in vitro plasma distribution similar to free drug. The majority of micellar PTX associated with the lipoprotein deficient plasma fraction (LPDP). In contrast, nanospheres were capable of retaining more of the encapsulated drug with significantly less PTX partitioning into the LPDP fraction. In conclusion, although both micelles and nanospheres were capable of solubilizing PTX and were hemocompatible, PTX nanospheres may offer the advantage of prolonged blood circulation, based on the in vitro plasma distribution data, which showed that nanospheres retained PTX more effectively.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 53-54). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Hong Kong, 2010. / Includes bibliographical references (p. 253-274). Also available online.

Thesis (M. S.)--Chemical Engineering, Georgia Institute of Technology, 2005. / Meredith, Carson, Committee Chair ; Prausnitz, Mark, Committee Member ; Bommarius, Andreas, Committee Member.

Thesis (Ph.D.)--Ohio University, November, 2005. / Title from PDF t.p. Includes bibliographical references (p. 165-167)

Leucotrienos e prostaglandinas são metabólitos do ácido araquidônico que, além de mediadores da inflamação são importantes imunomoduladores da liberação de citocinas, nas respostas imune inata e adquirida. Embora estes mediadores apresentem potencial para serem utilizados como adjuvantes ou imunomoduladores da resposta imune, eles são altamente instáveis, dificultando o uso in vivo. Por esta razão, estas substâncias foram incorporadas em um sistema polimérico microestruturado. Este foi constituído de microesferas de quatro a seis micrômetros de diâmetro, contendo leucotrieno B4 (LTB4) ou prostaglandina E2 (PGE2) incorporados na matriz polimérica (PLGA). A caracterização in vitro das microesferas de PLGA, contendo LTB4 ou PGE2, foi feita através da determinação da morfologia e medida dos diâmetros médios, taxa de encapsulação e perfil de liberação in vitro dos mediadores. Além disso, foi avaliada a preservação da atividade biológica do LTB4 liberado das microesferas, através do efeito do mesmo sobre a expressão de moléculas de adesão Mac-1 por citometria de fluxo. Também foram avaliadas a preservação da atividade biológica do LTB4 e da PGE2 liberados do interior das microesferas, através de estudos com microscopia intravital e a ativação de células endoteliais humanas (HUVECs e HUAECs). Realizamos ainda, ensaio de fagocitose com as microesferas contendo os dois mediadores encapsulados, utilizando macrófagos peritoneais murinos, além da avaliação da sobrevivência dos animais tratados intranasalmente com microesferas contendo LTB4 ou PGE2 durante a infecção pelo H. capulatum. Nestes animais, avaliamos a reação inflamatória pulmonar, o número de UFCs recuperadas dos pulmões e a modulação da resposta imune, através da quantificação de citocinas inflamatórias. Os estudos abordados neste trabalho revelaram achados interessantes e importantes quanto ao uso de microesferas biodegradáveis contendo mediadores lipídicos em situação de terapia, especialmente quando estes estão envolvidos em processos inflamatórios e/ou infecciosos. / Leukotrienes and prostaglandins are arachidonic acid metabolites, which participate in the inflammatory response and modulate cytokines release in both adaptive and innate immune responses. However, some physicochemical characteristics of these mediators, such as poor solubility in water and chemical instability, make them difficult to administer in vivo. In this sudy, we developed a polymeric microparticulate system for the encapsulation of lipid mediators. Regarding the in vitro characterization of the microspheres, we determined their diameters, evaluated the in vitro release of the mediators and the microspheres uptake by peritoneal macrophages. To assess the preservation of the biological activities of these mediators, we conducted intravital microscopy studies and determined the effect of LTB4 and PGE2-loaded biodegradable microspheres on inflammatory mediators release by murine peritoneal macrophages and human endothelial cells. In mice infected by H. capsulatum, we investigated the effects of intranasal administration of the microspheres on pulmonary inflammatory response. In this context, we analyzed the inflammatory cells recruited to the bronchoalveolar space, the mice survival and the number of CFUs recovered from the lungs after the administrations. We also assessed the cytokines release by the lung cells after the treatment with microspheres during the course of the infection. In conclusion, our findings showed that biodegradable microspheres could preserve the biological activity of the encapsulated mediators indicating their use as a new strategy to modulate cell activation, especially in the innate immune response.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A utilização de polímeros biodegradáveis é uma das formas de minimizar o grande volume de descartes de materiais poliméricos que tendem a aumentar cada vez mais causando dano ao meio ambiente. Existem vários métodos de avaliação de biodegradação de polímeros que podem contribuir para o desenvolvimento de novos materiais biodegradáveis. Nessa dissertação foi avaliada a biodegradação do compósito de matriz de polímero comercial à base de poliéster e amido e fibra de coco verde. Foram usados dois métodos, em solo simulado e em ambiente marinho. A biodegradação dos compósitos foi avaliada através das análises de: Perda de massa, Microscopia ótica (MO), Microscopia Eletrônica de Varredura (MEV), Calorimetria Diferencial de Varredura (DSC), Análise Termogravimétrica (TGA) e Espectroscopia na região do Infravermelho (FTIR). Além disso, foi realizada uma comparação entre desempenho de biodegradação do material nos dois ambientes. A velocidade de biodegradação no ambiente marinho é maior do que no solo simulado / The use of biodegradable polymers is one of the ways to minimize the large volume discharges of polymer materials which tend to increase causing more damage to the environment. There are several methods for evaluation of polymer biodegradation which can contribute to the development of new biodegradable materials. In this dissertation was evaluated the biodegradation of a polymer composite commercial with matrix based on polyester and starch and green coconut fiber. Two methods were used, simulated soil and marine environment. The biodegradation of the composites was evaluated by mass loss, optical microscopy (OM), Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Infrared Spectroscopy (FTIR). In addition, it was performed a comparison between the biodegradation of the material in both environments. The biodegradation rate of the marine environment is greater than the simulated ground

Made available in DSpace on 2015-04-17T14:49:42Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1556222 bytes, checksum: ff5f5ab067a6252f9aef5be2f52b8e69 (MD5) Previous issue date: 2014-03-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The Brazilian production of marine shrimp is mainly focused on the domestic market, which better absorbs the headless and peeled product, which generates significant amount of agro-industrial waste. The objective of this research was to develop biodegradable films of chitosan from the exoskeleton of marine shrimp vannamei Litopeanaeus added liquid smoke for use in sausages. For characterization of chitosan obtained from the exoskeleton of shrimp were employed methodologies for determining viscosity , conductometry , spectroscopy in the infrared and x-ray diffraction to characterize the polymer and performed tests of tensile strength , elastic modulus , solubility , opacity and thickness to characterize the films . The results were efficient for the determination of chitosan, and consistent with the literature regarding the characterization of polymeric films of origin. Microbiological analyzes were performed on the sausages before and after preparation according to ANVISA Resolution on January 12, 2001, in the chitosan films with and without plasticizer added to liquid smoke for coating sausages in order to increase the shelf life of the product the antimicrobial activity of the films was determined by the agar diffusion method on bacterial strains: Escherichia coli active, Pseudomonas aeruginosa and Staphylococcus coagulase positive. In the results , not presence of coliforms at 45 º C , coagulase Staphyilococcus positive , were observed Clostridium sulfite reducer was not detected the presence of Salmonella sp, as the antimicrobial activity , inhibition zones were found in biofilm added liquid smoke , only to Escherichia coli. As for the sensory properties of sausages packaged in three types of biodegradable chitosan film extracted from the exoskeleton of marine shrimp were differentiated by the addition of liquid smoke concentrations: 5 %, 7% and 10%. A nine-point hedonic scale was used to analyze the difference of control and acceptance testing were assessed using internal preference mapping (MEDPRF). The results indicated a significant difference between the control, conventional polyethylene film and biodegradable chitosan film plus smoke. By Preference Mapping revealed that the coated film containing sausages with liquid smoke in concentrations of 5 % and 7 %, no statistical differences obtained for the attributes: Appearance, Aroma, Taste, texture and overall acceptance levels in the addition of adding smoke compared to the control sample and 10 % ¨ smoke. It was observed in this work that the mechanical analyzes of biodegradable chitosan film is presented as a low elasticity and high tensile strength , and acceptable as opacity, solubility and thickness and that more research needs to be conducted in order to prepare chitosan films more flexible and resistant. / A produção brasileira de camarão marinho está voltada principalmente para o mercado interno, que absorve melhor o produto descabeçado e descascado, o que gera quantidade relevante de resíduos agroindustriais. O objetivo desta pesquisa foi o desenvolvimento de filmes biodegradáveis de quitosana a partir do exoesqueleto do camarão marinho Litopeanaeus vannamei adicionados de fumaça líquida, para aplicação em salsichas. Para caracterização da quitosana foram empregadas as metodologias de determinação da viscosidade, condutimetria, espectroscopia na região do infravermelho e difração de raio-x para caracterização do polímero e realizados os testes de resistência a tração, módulo elásticos, solubilidade, opacidade e espessura para caracterização dos filmes. As análises microbiológicas foram realizadas nas salsichas antes e após acondicionamento segundo a Resolução da ANVISA no 12 de janeiro de 2001, nos de filmes de quitosana com e sem plastificante adicionada de fumaça liquida, para o recobrimento de salsichas visando o aumento da vida de prateleira do produto ,a atividade antimicrobiana dos filmes foi determinada mediante teste de difusão em ágar sobre as cepas bacterianas: Escherichia coli ativa, Pseudomonas aeruginosa e Staphylococcus coagulase positiva. Nos resultados, não foram observadas presença de coliformes a 45 ºC, Staphyilococcus coagulase positiva, Clostridium sulfito redutor e não foi detectada a presença de Salmonella sp, quanto à ação antimicrobiana, foram encontrados halos de inibição no biofilme adicionado de fumaça liquida, apenas para Escherichia coli. Quanto às propriedades sensoriais de salsichas embaladas com três tipos de filme biodegradável de quitosana foram diferenciadas pela adição de fumaça liquida nas concentrações de 5%, 7% e 10%. Uma escala hedônica de nove pontos foi empregada para analise de diferença de controle e os testes de aceitação foram analisados pela metodologia de Mapa de Preferência Interno (MEDPRF). Os resultados indicaram que houve diferença significativa entre o controle, filme convencional de polietileno e os filmes biodegradável de quitosana acrescidos de fumaça líquida. Pela análise do Mapa de Preferência observou-se que as salsichas recobertas com filme contendo fumaça liquida nas concentrações de 5% e 7%, não diferenças estatísticas obteve para os atributos: Aparência, Aroma, Sabor, Textura e Aceitação global na adição teores de adição de fumaça, quando comparados com a amostra controle e 10¨% de fumaça. Foi possível observar que as análises mecânicas do filme biodegradável de quitosana apresentaram-se como de baixa elasticidade e alta resistência a tração, e aceitáveis quanto a opacidade, solubilidade e espessura e que mais pesquisas precisam ser realizadas a fim de elaborar filmes de quitosana mais flexíveis e resistentes. Concluímos que os resultados encontrados foram eficientes para determinação da quitosana, e compatíveis com a literatura quanto à caracterização de filmes de origem polimérica.